Halfway through: Dragon Avenger. I feel the book is a copy of the first one: Dragon Champion, so I would not recommend it. It doesn't add anything new and I fail to feel captivated by the story. On the other hand with the Temeraire series I felt with the characters and couldn't wait to read the sequels.

My wife just read Dragonhaven by Robin McKinley, and enjoyed it. We got it from Fictionwise.

I'd like to second this recommendation - I really enjoyed it.

I also second/third/etc. the Temeraire books. The human characters are nothing special, but I really enjoyed the dragons in them.

When I was in high school, I really liked the trilogy by Melanie Rawn that began with Dragon Prince. I was in high school though, and that was quite awhile ago, so I don't know if I'd trust my judgement today . There are some books that I loved in high school that I still love today, and some that upon re-reading many years later I wonder what I was thinking; having not read these since high school, I'm not sure if this series would fall under the former or latter category.

I can't let this question go by without pointing out my own two science fiction (not fantasy) dragon novels, Dragons in the Stars and Dragon Rigger. They're both in ebook, multiformat. (They're in most of the ebook stores, but I recommend either fictionwise or webscription for DRM-free versions.) You can read the short story that the first book was based on, "Though All the Mountains Lie Between," on my website for free.

My family also really enjoyed Patricia Wrede's series, which I believe started with Dealing with Dragons. And Jane Yolen wrote a good YA trilogy, the Pit Dragon series.

If you're having trouble remembering names/places this book is perhaps not so easy since there's a lot of places and names to remember, especially in the following books.
I'm currently on book 3 in the series and I still find the story interesting.